BlocProvider

Provide Cubit to the tree with BlocProvider.

BlocProvider

BlocProvider provides a Cubit or Bloc to the widget tree. The create parameter takes the function that produces the Cubit instance.

BlocProvider<CounterCubit>(
  create: (_) => CounterCubit(),
  child: Screen(),
)

The Cubit is automatically closed when it leaves the tree.

create and child

create is called when BlocProvider is first needed. child is the widget subtree under the provider.

BlocProvider<CounterCubit>(
  create: (_) => CounterCubit(),
  child: MaterialApp(home: Screen()),
)

The Cubit's lifecycle is managed by the provider.

Exercise Provide Cubit with BlocProvider

Provide the Cubit to the tree with BlocProvider<SayacCubit>. Create a new SayacCubit() instance with create. In main, call print('uygulama başladı').

Show example solution

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

class SayacCubit extends Cubit<int> {
  SayacCubit() : super(0);
}

void main() {
  print('uygulama başladı');
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider<SayacCubit>(
      create: (_) => SayacCubit(),
      child: MaterialApp(
        home: Ekrani(),
      ),
    );
  }
}

class Ekrani extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(body: Center(child: Text('ekran')));
  }
}

Test yourself

When is BlocProvider's create called?
- When the app closes
- On every build
- When BlocProvider is first needed
- Only on error
Show answer

When BlocProvider is first needed — BlocProvider's create function is called when the provider is first needed, producing the Cubit instance.

Give BlocProvider the Cubit type

BlocProvider<____>(
  create: (_) => SayacCubit(),
  child: Ekrani(),
)

Show answer

BlocProvider<SayacCubit>(
  create: (_) => SayacCubit(),
  child: Ekrani(),
)

BlocProvider parts

BlocProvider

Provides Cubit to the tree
create

Produces Cubit on first need
child

Widget subtree under provider
close

Called when Cubit is disposed

Next lesson: BlocBuilder

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